Solar cells, grouped in panels, harness solar energy and convert it into electricity. Each individual cell produces a small amount of electricity, which is added to that produced by the other cells in the panel, resulting in a usable amount of electricity being produced.
Solar cells are made from wafers of highly refined silicon. Silicon is a semi-conductor that holds its electrons more tightly to itself than a metal like copper. By doping the silicon with boron or phosphorous, the silicon can be made to give up its electrons easier.
Silicon, with its four electrons in the outer shell, makes up most of the solar cell. Boron atoms, which have three outer shell electrons, are present throughout the silicon wafer. A layer of phosphorus which has five electrons in its outer shell forms a thin layer across the surface of the cell.
Some of the electrons from the phosphorus cross over to the silicon wafer and fill the "holes" in its electron shell. The holes occur where the boron atoms are present since boron has one less electron than silicon. The silicon holds tightly to these electrons, creating an imbalance of electrical charges between the phosphorus and the silicon wafer. This imbalance creates an electrostatic field across the surface of the phosphorus. It is this field that makes a solar cell work.
Sunlight is made up of photons, which can be thought of as tiny particles of energy. When a photon strikes an electron, it gives that electron its energy and allows it to break free of the silicon's grasp. Thus the energy of the photon allows electrons to flow. The flow of electrons is electrical current.
The electrostatic field pushes the electrons to the front of the solar cell. They lose some energy as they pass through the field, but manage to keep half of it. The voltage potential of a single solar cell is only 1/2 volt, only 1/3 that of a typical flashlight battery. This is why solar panels are made up of many solar cells.
Solar cells are connected in series in modules of 36. At 1/2 volt each, that makes 18 volts. Multiple modules can be connected in series to produce more voltage. The voltage flows in a circuit to charge a battery bank or run a DC to AC inverter. The electrons lose their energy in the process and return to the silicon wafer in the solar cell. The process starts all over again.